System of distribution



Jul '20 ,1926.

- 1,593,355 D. c. PRINCE v SYSTEM DISTRIBUTION Filed Jui 13 192s" I nVenBor DA/Fd. C.Pr-inoe,

Patented duly 2t), 192 6. I

UNITED STATES.

DAVID c. PRINCE, OF sOHENE TADY, NEw YOnx, ASSIGNOR 'I.O GENERAL ntncrmo COMPANY,'A CORPORATION OF NEW YORK.

SYSTEM OF DISTRIBUTION.

Abnlicationfiled Jul -13, 1923. Serial No. 651,410.

My present invention relates tofsystems of electrical distribution in which it isidesiredto change direct current of one voltage to direct current of another voltage.

In systems involving the transmission of large amounts of electrical energy for considerable distances it has become customary to employ'high voltage alternating currents. One of the advantages of such a system which renders it peculiarly suitable for eleci I .trical power distribution is the comparative simplicity of the apparatus required for transforming the low voltage current generated to high voltage for transmissionfand in turn transforming the highv'oltage current transmitted to a low voltage suitable for utilization. i

It has long been recognized that a high voltage direct currenttransmission system would have certainadvantages over an alternating current system, but it has not been possible to fully realize these advantages because of the impossibility of directly gencrating the high voltage desired and the lack'of suitable apparatus for efficiently con verting the transmitted high voltage direct currentto a voltage suitable for utilization. One of the objects of my invention is to provide a simple and efficient apparatus which is capable of converting direct current of any voltage to direct current of any other desired voltage, one of which voltages may be high enough to permit of the coo-- age alternating current to low voltage alternating current for direct utilization or for rectification to produce direct current of a desired voltage. v A further object of my invention is to provide apparatus whereby one or more of the steps referred to in the system described may be carried out more eficiently than has heretofore been possible. 7

In the operation of a rectifier, and also in a system forconverting direct current to alternating, it is desirable that momentary fluctuations in the direct current during the periods when thepath of flow of the current 18 changing should be avoided This is usually accomplished by someform of series .reactance. This reactance, unless the num-.

'ber of phases employed is four ,or more, is normally very large for. the work which it has to 'do because of the fact that it is sub jected to direct current saturation.

p A- further object of my invention is to provide a means whereby the size of the series reactance used maybe greatly reduced.

The novel features which I belie e to be characteristic of my invention are set forth With particularity in the appended claims.

My invention itself, however, both as toits organization and method of operation, to-

,gether with further objects and advantages thereof, will best be understood by reference to the following description taken in connection with the accompanying drawing in whlch I have shown diagrammatically one,

circuit organization whereby my invention may be carried into efi'ect.

I have indicated in the drawing a system in which direct current from the mains 1 and 2 is supplied through the plate circuits of the thermioniovalves 3 and l to the primary winding 5 of a transformer of the de-.. sired ratio oftransformation having a secondary winding 6, the hpposite terminals of which are connected to the anodes of thermionic rectifiers 'Z and 8. Direct current main 1 is connected to the middle point 9 of winding 5 through reactance 10, and main 2 is connected to the cathodes of valves 3-and 4 so that current impulses supplied to the winding 5 by the two valves, flow 1n opposite directions through windlng 5. The

valves are controlled in the desired manner by means of voltages applied to their grids; which are supplied from v the secondary winding 6 through the connecting leads 11 and 12. A load circuit to which the rectified current from rectifiers 7 and 8- is supplied, is connected from the middle point 13 of secondary 6 through reactance 14, and the load. devices 15 to the cathodes of 'rectitiers 7 and 8.. i

The frequency Of the oscillations produced may be determined by means of a condenser 16 connected across the primary windingb. In the operation (:f a system or the type described it is necessary for efiicient and satisfactory operation that current a should be-allowed to start in one valvebeare at the same potential.

fore it is completely interrupted in the other valve, and that" the current transfer should take place in advance of the point in the cycle at which the plates of valves 3 and 4 which carry the direct current component of plate current. The drop through condensers 17 is in quadrature lagging 90 behind the current so that when the-tubes'botlr become conducting there is still a potential difference between the anodes in the direction to' stop the currentin the tube about to be'cut off and to start current in the tube which has just become conducting. The reactances '10 and 14 are in inductive. relation, being wound upon a common core. lVhen the potential wave generated in windings 5 and 6 is passing through zero, no voltage will be supplied to the rectifiers 7' and 8,.and no counter-electron'iotive force will be supplied to the valves 3' and fl. Under these conditions the current in the output line tends to fall while the current in theinput line tends to rise. These two tendencies are opposed to one another through the transformer 1014, which should have the same ratio as the main transformer 5+6. Thus the lack of direct current voltage and counter electromotive force of the main "transformer at this point is compensated for by the voltages induced in the transformer 10l4. At the same time the direct currents in the two windingslO and 14 have an opposite magnetizing effect upon the core so that there is no direct current saturation effect, and

transformer 101 l may be made a com paratively small and compact device. The voltage effects are 'of the same nature through other parts of the cycle. Thus when the voltages in the transformer 5-6 are at their peak the voltage on the rectifiers is higher than that required by the Since the cur-' load, and at: the same time the counter-electromotive force is higher than the impressed electromotive force onthe primary 5. The

potentials in the windings 10,14 then'opcrate in the opposite direction.

WVhile I have shown and described only one embodiment of my invention it is apparent that my invention is not limited to the precise embodiment shown as many modifications in the mannerof carrying my invention-into efi'ectmay be made without with said primary winding, and a rectifyin dcvice'connected to said secondary win ing and connected to a. load circuit through a reactance which is inductively re- [ated to the first mentioned reactance.

2. The combination in a system of electrical distribution of a source of direct-current, a primary winding connected'to said source through a reactance and a plurality of electric valves, means for controlling the action. of said valves to supply current im-j pulses to said winding atpredetermined intervals, a secondary winding inductively as.- sociated with said primary Winding, and a rectifying device connected to said secondary winding, and. connected to a load circuit through a reactance which is inductive lated to the first mentioned reactance.

3. The combination in a system of elect-ricaldistribution of a source of direct current,.'a primary winding having its terminals connected to the anodes of a pair of electric'valves and its mid'pdint connected to said direct current source through a reactance, and a secondary winding inductively associated with said primary winding having its terminals connected to the anodes of a rectifying device, and connected to a load circuit through a reactance which is inductively related to the first-mentioned reactance.

In witness whereof, I have hereunto set my hand this 3rd day of July, 1923.

DAVID C. PRINCE.

its mid point 

